COMPARATIVE-ASSESSMENT OF BIOLOGICAL EFFICIENCY OF CROSSBRED LAMBS FROM 2 COMPOSITE LINES AND DORPER SHEEP

Reproduction, growth and biological efficiency of two Composite dam li nes, developed from Finnsheep and indigenous breeds, were investigated and compared to Dorpers. Composite and Dorper ewes were mated to Dorp er rams. Ewes were exposed to three 30-d joining periods in 2 years. L itter size was 1.35, 1.48 and 1.08 lambs born to Composites 1, 2 and D orpers, respectively. Lambs born per lambing opportunity (fecundity) w ere 0.88, 0.93 and 0.75 for the three groups, respectively. Birth weig hts (BW) of lambs of Dorper ewes were higher than those of Composite e wes (P less than or equal to 0.05), but not weaning weight (WW) (at ap prox. 63 d) or 100 d weight (100 W). Cumulative DDM intake (DDMI) was 49% greater in Dorper ewes than in Composites. Total carcass weight (C W) and carcass energy content produced (E) per ewe was higher in Dorpe r, while CW/100 kg DDMI and E/kg DDMI were higher in Composites. In te rms of these efficiency parameters, Composites were 84 and 79% more ef ficient than Dorpers in the 2-yr period. Ewes producing twins were 43% more efficient than those producing singles. Optimum efficiency was c alculated at approx. one twin slaughtered every 8 months. Results demo nstrated that owing to the outstanding performance and small size of t hese Composites, efficiency can be improved considerably by using them in crossbreeding systems.